Hydraulic lifting jack



Dec. 1, 1931. L. D. NlLsoN 1,834,547

HYDRAULIC LIFTING JACK Filed Dec. 3l, 1928 2 Sheets-Sheet l Jill/laici',Z zand/d 17, 72H10@ Dec. 1, 1931. L. D. NlLsoN HYDRAULIC LIFTING JACKFiled Deo, 3l, 1928 2 Sheets-Sheet 2 Jaz/miaf *Liana/fa 2 ,Wi/Jamfiar/vg.:

Patented Dec. 1, 1931 UNITED STATES PATENT OFFICE LEONARD D. NILSON, OFWAYZATA, MINNESOTA, ASSIGNOB TO MARQUETTE MANUFAC- TURING COMPANY, 0FST. PAUL, MINNESOTA y HYDRAULIC LIFTING J' ACK .Application led December31, 1928. Serial No. 329,326.

10 means consisting of a check valve and a release valve, one of whichmay be opened by the operating handle being positioned at apredetermined point and the other thereof, controlled by an independentcontrolling Still a further object is to provide a construction in whichthe independent controlling means is operable only upon the operatinglever assuming the predetermined posi- 20 tion for opening the checkvalve.

Still a further object is to provide a flexible connecting means for thecontrolling mechanism for the purpose of opening the re-` verse valveand which assumes a substantially taut position only upon the operatinghandle assuming the position for opening the check valve,

With these and other objects in view my invention consists in theconstruction, arrangement and combination of the various parts of mydevice, whereby the objects contemplated are attained as hereinaftermore fully set forth, pointed out in my claims and illustrated in theaccompanying drawings. Although the invention is susceptible of avariety of embodiments, it is unnecessary to fully ldescribe andillustrate more than one in order to give a full understanding of theinvention both from its structural and functional standpoints.Accordingly, I have v illustrated a preferred and desirable embodimentof the invention in the accompanying drawings in which: i

Figure 1 is a plan view of my jack structure, part of the operatinghandle being cut olf. f

i Figure 2 is aplan view of the part of the operating handle not shownin Figure 1.

Figure 3 is a side elevation of my structure showing the lifting head inraised position by means of dotted llnes.

Figure 4 is a side elevation of the outer end of the operating handle.

Figure 5 is a detail sectional view on the i line 5-5 of Figure 1.

Flgure 6 1s an enlarged sectional view onA the line 6-6 of Figure 1.

Figure 7 is a sectional view on the' line 7-7 of Figure 1, illustratingthe operating handle in raised position.

Figure 8 is an enlarged sectional view of a portion of Figure 7 showingthe parts in a different position; and

Figure 9 is a detail sectional view on the line 9--9 of Figure 8.

On the accompanying drawings I have used the reference numeral 10 toindicate the front axle of my jack. Wheels 12 are rotatably mounted onthe axle 10. Rear Wheels 14 are provided for the jack structure and areof the swivel or caster type. Each wheel 14 is swivelly mounted in hubs16 .formed on brackets 18.

The frame of my jack consists of side bars 20 and castings 22. The frontaxle 10 is secured to the frame members 22 and the brackets 18 aresecured to the side bars 20. The members 20 and 22 are bolted togetheras clearly illustrated on the drawings. At the rear end of the jackframe, a cross member 24 serves to space the side bars 20.

The frame members 22 extend rearwardly and upwardly and terminate inportions adapted to support a pivot bolt 26. Pivoted on the bolt 26 is alifting arm 28 having a lifting head 30 pivotally mounted on the outerend thereof. The connection between the lifting head 30 and the liftingarm 28 is shown at 32 in Figure 1 of the.drawings. In con` nection withthe lifting head 30 I provide stabilizing arms 34 pivoted to arms 36extending from the lifting head 30 and to pivot bolts 38 in the framemembers 22.'

For swinging the lifting arm 28 and consequently, raising the liftinghead 30 I provide a hydraulic mechanism consisting of a cylinder 40 anda piston 42. The cylinder 40 is provided with -a head 44 having apivotal connection by means of a pin 46 to the lifting arm 28.

As clearly illustrated in Figure 5, the lifting arm 28 is triangular inshape and the pin 46 is mounted. at one corner of the trian le. Thepiston 42 is mounted on a piston ro 48 -Which in turn is secured to thehub 50 of a yoke 52. The arms of the yoke 52 are piv.

oted by means of bolts 54 to forwardly extending frame members 56located at the rear end of the ack.

From the construction of the parts just described, it will be obviousthat the cylinder 40 may be moved relative to the piston 42, the pistonitself being mounted stationary relative to the frame of the jack andthe cylinder in formation and thus provides a pump cylinder for theplunger 60.

As shown in Figure 6, the forward end of the plunger 60 is provided witha fitting 62 4 to which a cup-leather 64 is secured by means of afitting 66. The cup-leather 64 servesthe purpose of sealing againstleakage of oil past the plunger and through the piston rod or pumpcylinder 48.

The piston 42 itself is of cup-leather construction and secured to apiston head 68. Within the piston head 68, inlet and outlet check valvesand 72 are provided. Thus a tubular piston rod 48, plunger 60 and checkvalves 70 andv 72 form a pump for pumping oil from the rear side of thepiston head 68 to the forward side thereof for the purpose of moving thecylinder `40 relative to the piston 42.

In the piston head 44 a check valve 74 is provided which allows oil toby-pass from the passage 76 through a passageway 78 to the oil reservolr80 mounted above the cylinder 40. The reservoir 80 is covered by a coverplate 82 having a filler plug 84.

For allowing oil to iiow from the reservoir 80 .top the cylinder 40 onthe rear side of the plston head 68, I provide an opening 86 shown inFigure 5 of the drawings. In the event of an over-load being imposed onthe lifting head 30, oil from the pump structure will open the valve 74and thus the valve acts as a safety device. The spring 88 holding thevalve 74 in closed position, may be designed to take-care of any desiredoverload, the stronger the vspring the greater the load may be withoutopening the valve 74.

For reciprocating the pump plunger 60 and thereby actuating the valve 70and 72 and forcing oil from the rear side of the piston head 68 to thefront side thereof, I provide an operating handle 90. The handle 90 ispivoted at 92 to the rearwardly extending frame members 56. By means ofa latch 94 the operating handle is connected wlth an oscillatablymounted member 96. The latch 94 may be operated from the handle Portlon108 of the handle 90 by means of a lever 110. The latch 94 coacting withnotches 98 formed in the member 96, allows for adjustment of the handle90 relative to the member 96.

The oscillatable member 96 is operatively connected with the pumpplunger 60 by means of links 100. The links 100 are connected with themember 96 by a pin 102 and to the pump plunger 60 b means of a collarfitting 104. The pump p unger extends througha packing nut 106 on theouter end of the piston rod 48.

The pump plunger 60 is of hollow construction to receive a reverse valverod 112. The rod112 extends through a packing nut 114 in the outer endof the tubular pump plunger 60 and is provided with a ange 116. A yokeshaped lever 118 is pivoted between the links 100 ona pin 120. The armsof the yoke member 118 contact with the flange 116 on the valve rod 112.The valve rod 112 is provided with a collar 122 and a spring 124. Thespring 124 serves to hold the reverse valve 126 against itsseat in thefitting 62, at

the forward end of the plunger 60.

A flexible connection such as a chain 128 is provided for the yokemember 118. The chain 128 connects with a pull rod 130 terminating in ahandle portion 132 adjacent the handle .member 108. The pull rod 130 isprovided with a portion 134 adapted to extend through aslot 136 formedin one of the side bars of the operating handle as shown in Figure 2.

Practical operation In the operation of my jack, the member 96 may beoscillated for imparting lifting movement to the lifting head 30 bypumping the handle 108 upwardly and downwardly. This causes the pumpplunger 60 to draw oil through the inlet valve 70 and discharge itthrough the outlet valve 72 into the cylinder 40. This extends thehydraulic connection consisting of the cylinder 40`and the piston 42 sothat the lifting head 30 may be moved to the dotted lines position shownin Figure 3.

For lowering the jack it is necessary to move the operating handle 90 toits ,lowermost position whereupon the pump plunger 60 will assume theposition shown in Figure 6 of the drawings. In such position, a stem 67on the fitting 66 will open the valve 72 for allowing oil to iiow fromthe cylinder 40 in front of the piston head 68 and into the piston headitself.

It is now necessary to open the valve 126 so that oil may iow fromwithin the piston head 68 through the openings 61 and 49 formed in thepump plunger 60 and piston rod 48 respectively. The spring 124 isholding the valve 126 closed and to open the valve, the pull rod 132must be moved to the dotted line position shown in Figure 2.

It will be noted that the chain 128 is slack whenever the handle is upas shown in Figure 7 but is nearly taut when the handle is in` loweredposition as shown in Figures 3, 5 and 8. Thus it will be seen that thereverse valve 126 may be opened only when the operating handle 90 is inits lowered position where it may open the valve 72. Thus the operatinghandle may be utilized for ordinary raising operations and for part ofthe lowering operations but if it should be accidently moved to loweredposition, the jack will not .be lowered because the pull rod 132 must beoperated in conjunction with the lever 90 for lowering the lifting head.

Some changes may be madein the con-l struction and arrangement of theparts of my device without depart-ing from the real spirit and purposeof my invention, and it is my intention to cover by my claims anymodified forms of structure or use o mechanical equivalents, which maybe reasonably included within their scope.

I claim as my invention:

1. A jack structure comprising -a low wheeled horizontally arranged elonated frame, a lifting head mounted on said rame at one end thereof, anactuating mechanism on the other end of said frame, means of connectionbetween said mechanism and lift- Ving head including a hydraulic pumpstructure having a piston, a cylinder'mounted on stituting a reservoirfor the fluid actuating said structure, said cylinder having operativeconnection With the lifting head and movable therewith and relative tosaid piston and means located within the piston for allowing oil to betransferred from one side thereof to the other but normally preventingits return, a portion of said last means being operable independent ofover-operation of the means within the piston for the purpose ofallowing oil to flow in an opposite direction for lowering the liftinghead, and means within the head of said cylinder serving to by-pass oilfrom one side of the piston to the other side thereof when the jack isoverloaded.

2. A jack structure comprising a low wheeled horizontally arrangedelongated frame, a lifting head mounted on said frame at one endthereof, an actuating mechanism on the other end of said frame, means ofconnection between said mechanism and lifting head including a hydraulicpump structure having a piston, a cylinder mounted on and receiving saidpistonsaid cylinder constituting a reservoir for the fluid actuatingsaid structure, said cylinder having operative connection with thelifting head and movable therewith and ,relative to said piston andmeans located within the cylinder head and responsive to the loadimposed thereupon for Vsaid frame and its other end pivoted to saidlifting arm for swinging the same when the hydraulic mechanism isactuated, said mechamsln com rising a piston rod and a cylinder slidablere ative thereto and a pump structure in said piston rod, said pumpstructure including check valves, a reciprocable plunger, and meansactuated by over reciprocation thereof to open one of said check valvesfor allowing oil to flow therethrough, means within said plunger toallow said oil to ass by the other check valve and a rod wit in theplunger and reciprocable to operate said last mentioned means.

4. In a jack structure, a frame, a lifting arm pivoted thereon and ahydraulic actuat- 1n said frame and its other end pivoted to saidlifting arm for swinging the same when the hydraulic mechanism isactuated, said mechanism comprising a piston rod and a cylinder slidablerelative thereto and a pumpstructure in said piston rod, said pumpstructure including check valves, a reciprocable plunger, and meansactuated by over reciprocation thereof to open one. ofsaid check valvesfor allowing oil to flow therethrough, means within said plunger toallow said oil to pass by the other check' valve and a rod within theplunger, controlled externally thereof and reciprocable mentioned means.

5. In a jack structure, a frame, a lifting arm pivoted thereon and ahydraulic actuating mechanism having one end pivoted to said frame andits other end pivoted to said lifting arm for swinging the same when theto operate said last Vhydraulic mechanism is actuated, said mechamsmcomprising a piston rod and a cylinder slidable relative thereto and apump structure in said piston rod, said pump structure including checkvalves, a reciprocable plunger, an oscillatable handle for reciprocatingsaid plunger, and means actuated by over reciprocation thereof to openone of said cheek valves for allowing oil to flow therethrough, meanswithin said plunger to allow said oil to pass by the other check valveand a rod within the plunger and reciprocable to operate said lastmentioned means, said handle being provided with control means thereonto reciprocate said rod.

6. In a jack structure, a frame, a lifting arm pivoted thereon and ahydraulic actuating mechanism having one end pivoted to mechanism havingone end pivoted to A lll said frame and its other end pivoted to saidlifting arm for swinging the same when the hydraulic mechanism isactuated, said mechanism comprising a piston rod and a 5 cylinderslidable relative thereto and a pump structure in said piston rod, saidpump structure including check valves, a reciprocable plunger, anoscillatable handle for reciprocating said plunger, and means actuatedby l0 over reciprocation thereof to open one of said check Valves forallowing oil to flow therethrough, means Within said plunger to al- Wsaid oil to pass bv the other check valve and a rod within the plungerand reciprocable to operate said last mentioned means, said handle beingprovided With control means thereon to reciprocate said rod, saidcontrol means being operable only when the handle is in a predeterminedposition. LEONARD D. NILSON.

